(In the quoted examples, the "_" sign represents an empty space)
Note that there are some minus signs and no spaces, in the example above the first character of the first line is an empty space, so each number spans 10 characters.
With the command cut -c1-10 I can get the correct numbers but only the first column of the input file, and I don't know how to reorder the numbers.
Any suggestions?
If Franklin52's solution fails for anyone trying it, it's because the \n escape sequence in replacement text is an extension not supported by all implementations. If your implementation (like mine) does not support it, you need to use a backslash immediately prior to a newline to get the newline in there. Just mentioning it in case someone finds themselves scratching their head
$ sed 's/\(.\{10\}\)\(.\{10\}\)\(.\{10\}\)\(.\{10\}\)/\1\n\2\n\3\n\4/' data
_1.012E+01n_2.102E+04n_3.222E+03n_4.100E+02
-1.144E+02n-2.489E-02n_5.444E+01n-3.122E-03
-3.566E+00n_7.455E+04n-4.326E+03n_7.834E+00
$ sed -e 's/\(.\{10\}\)\(.\{10\}\)\(.\{10\}\)\(.\{10\}\)/\1\
> \2\
> \3\
> \4/' data
_1.012E+01
_2.102E+04
_3.222E+03
_4.100E+02
-1.144E+02
-2.489E-02
_5.444E+01
-3.122E-03
-3.566E+00
_7.455E+04
-4.326E+03
_7.834E+00